Capsule-type medical apparatuses that have spiral ridges, extending along the longitudinal axes, formed on the outer circumferential surfaces of substantially cylindrical capsules thereof and that include, in the capsules, permanent magnets whose magnetic poles are aligned in a direction orthogonal to the longitudinal axes are well known (refer to, for example, Patent Document 1).
In such a capsule-type medical apparatus, the capsule can be rotated about the longitudinal axis thereof by drawing upon the property that the permanent magnet therein rotates so as to align its magnetic-pole direction in the direction of an external magnetic field produced in a working space thereof when the external magnetic field is rotated about the longitudinal axis of the capsule. Since the spiral ridge is formed on the outer circumferential surface of the capsule, when the capsule is rotated about the longitudinal axis thereof while the spiral ridge is in contact with, for example, tissue outside the capsule, the rotational motion about the longitudinal axis is converted into propulsive motion in a direction along the longitudinal axis by means of the spiral ridge. In this manner, the capsule can be guided to a desired position using its ability to move in a direction along the longitudinal axis thereof.
Furthermore, capsule-type medical apparatuses having, in substantially cylindrical capsules thereof, permanent magnets whose magnetic poles are aligned in the direction of the longitudinal axes of the capsules are also known (refer to, for example, Patent Document 2).
In such a capsule-type medical apparatus, the orientation of the capsule can be changed by moving the permanent magnet therein so as to orient itself along a direction of an external magnetic field produced in the working space of the capsule-type medical apparatus. In addition, the capsule can be propelled in the direction of the longitudinal axis thereof by changing the external magnetic field to a gradient magnetic field.
Furthermore, a known example of an intrasubject insertion apparatus that is inserted into a body cavity and advanced while rotating is described in Patent Document 3. The intracorporeal guiding device described in this Patent Document 3 has an inflatable and deflatable membrane member, constituting a spiral-structured portion, formed on the outer surface of a rotating member provided at a front-end portion of an endoscope thereof. In this intracorporeal guiding device, the above-described membrane member is wound so as to extend obliquely with respect to the center of rotation of the rotating member. By doing so, as the above-described rotating member is rotated, the rotating member is endowed with a propulsion force through a screwing operation relative to a wall in the lumen, thereby propelling the front-end portion of the endoscope.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2004-255174
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2003-111720
Patent Document 3: Japanese Examined Patent Application, Publication No. S60-56488